Processing egg yolks



March 29, 1960 PUMP PUMP

l6' WATER VALVE DIVERSION VALVE TO WASTE VACUUM CHAMBER HEATER THERMOCOUPLE FILLING HOMOGENIZER J. JANAK ETAL 2,930,705

PROCESSING EGG YOLKS Filed March 20, 1957 mxms TANK COMMIUUTEK FLAKER {HIGH PRESS. DIVERSION VALVE PUMP TO coumzusms g VACUUM squwmzm' 1 JOHN JANAK FRANK R. HUMBURG RUFUS C. HILL IN V EN TORS A TTORIVEY United States Patcntb PROCESSING EGG YOLKS John Janak, Clarendon Hills, Frank Hnmbnrg, Hinsdale, and Rufus C. Hill, Park Forest, 11],, assignors to fix'iisft & Company, Chicago, 111., a corporation of Illi- Application March 20, 1957, Serial No. 647,390 1 Claim. (Cl. 99-182) s The present invention relates to the processing of egg yolk and provides an improved method for preparing a commercially sterile, shelf-stable, precooked, canned egg yolk. product having a smooth, uniform texture and consistency. V Y I The canned egg yolk product produced by the method of this invention is composed ofv egg yolk, salt and water,

with or without other flavoring materials such as meats, fru1ts, cereals, and milk. Salt (NaCl) is added 'to give anamount of approximately 0.8% in the finished product for flavoring purposes only. A desirable use of this product is for the feeding of infants. An advantage of the product in relation to that use is that it is of lesser viscosity than products that have been produced heretofore. YA

' further. advantageof-the product is that it may be reessed in accordance with this invention is that it retains its liquid characteristics whereby the material may be withdrawn through a straw or tube directly fromits container. V

We are aware of other prior art methods for processing egg yolk. But such methods are deficient in their ability to produce a uniformly low viscosity product which may be fed to an infant by either a nursing bottle or a spoon, or for m-fhght feeding. The instant process is, therefore, an improvement over the known processing procedures. Thus, an object of our invention is to provide an improved process for preparing a canned egg product hav-' ingimproved and desirable physical characteristics.

The method of our invention moves a mixture of egg 7 yolksand water through an indirect heating zone in which the mixture is heated to temperatures, which'the prior. art considered toibe unreasonably' high, to substantially'coagulate the egg yolk proteins.

smooth non-lumpy consistency andtexture. We-prefer that the product be cooled to'with'in the ra-nge of 80 to h 100 F. for we have found that this range produces'the' most satisfactory product; -The c'ooled product is then canned by either well-known asepti c'techniques or con ve'ntional methods in which the cans are retorted to'yield commercially-sterile shelf-stable products;

Another 1 The heated product is not held at treatment temperatures; but, is cooled immediately to a temperature, generally below approximately 130'F.,'.' which will produce a product li'avin'g' a permanently transferred to a mixing vat 13.

- merged to reduce air entrapment during mixing.

Patented Mar. 29,1960

will be referred to in describing the steps of our process of preparing a canned egg yolk product.

Frozen egg yolks areput through a conventional flaker 11 which discharges the flaked yolks into a conventional comminuting machine 12; the comminuted yolks are In vat 13, water and a small amount of salt is admixed with the comminuted egg yolks. The contents of thevat are mixed by appropriate agitating paddles which are preferably completely sub- In an alternative, thawed or fresh egg yolks may be comminuteddirectly in the'comminutor 12, in which case there would be no need'for the frozen product fiaker 11. i

From the mixing vat 13 the 'egg yolk-water mixtureis transferred to a holding vat 14 which acts as a constant supply source for the continuous operation of our pre-' ferred processing system. A pump 15 transfers the product from vat 14 to a high pressure pump 17 through flow diversion valve 16. Pump 15 furnishes a constant feed to the high pressure pump 17. The high pressure pump 17 discharges the product into an indirect heat exchange 18, which is composed of coiled stainless steel tubing of relatively small diameter and steam jacketed. From the heat exchanger 18 theproduct flows through a pressure regulating valve 19 and thence through a flow diversion valve 20 into a vacuum chamber 21 where the heated product is deaerated and rapidly reduced in temperature to below 130 F. by flash evaporation. The cooled product is then pumped from the vacuum chamber 21 by pump 22 to ahomogenizing unit 23 and thence to a container filling and closing machine (not shown).

Operating conditions within the heat treating section of v the system should be established before the egg yolk; water mixture is placed on stream. This is accomplished by admitting water to the system through the flow diversion valve 16 which is integrally connected with flow diversion valve 20 by control means (not shown). The water is pumped by pump 17 through the heater 18 pres-f} sure regulatingvalve 19 and discharged through fio'w diversion valve 20 to waste. When the desired operating temperatures are obtained, diversion valve 16 is repositioned, cutting oil the water supply and admitting the egg yolk product from pump 15 into the system. 'Ihewater- Theaccompanying drawing is a flow diagram which continues to divert to waste through valve 20, and after a predetermined time, the flow diversion valve 20 is closed, diverting the egg product to the cooling chamber 21.

A thermocouple 24 is connected to diversion valve 20v and is positioned to sense the temperature of product flowingfrom heater 18. Should the producttemperature from heater 18 fall below thetdesiredtreatment tempera:

ture, as indicated by the temperature sensing element 24, the flow diversion'valve 20 will automatically divert the sub-temperature product to waste. If the situation cannot be corrected immediately, valve 16 is changed toad -Q mit water to the'system until theioperating temperatures are abain obtained, after which time the product flow --wi-l1- be reinitiated, thereby allowing the continuous processing of ouregg yolk product. H .7, The'dis charge line from the indirect heat {exchanger is to the'vacuum chamber 21 'should be as short as possible i so that substantially no holding of the heated product o'c'cursj Valve 19' is placed in this lineto stepdownthe", pressures tosu'b-atmospheric and avoid cooling of thejhot; product up to the time it leaves tl 'eh'eate'r. o 1

In "one preferred installat'ion, anegg-water-salt mixture,

containing approximately 24.5 total solids, was pumped by the hig Pressure pump, 17 through a heating coil 18 (229 feet long with an internal diameter of 0.334 inch and an outside diameter of 0.5 inch) at a flow rate of approximately 40 pounds per minute, and the product was heated to a temperature of 310 F. The heated product was not held at the treatment temperature but immediately discharged into the evaporation chamber 21 where it was rapidly cooled to a temperature of 87 F. by flash evaporation and removal of a portion of the water of the initial egg yolk-.water mixture. The cooled mixture was canned in glass jars and retorted at a temperature of 235 F. for 75 minutes. The finished product had a total solids content of 29.9%. Proper sterilization of the canned product may be obtained by the use of various times. and temperatures sufficient to commercially sterilize the product. We prefer to use 235 F. for 75' minutes which will satisfactorily sterilize the product.

Alternatively, the product may be asepticallyfilled and sealed in presterilized cans. All of the aseptic canning equipment used in our process, including the filling and sealing machine, is old and well known to the art. In employing this alternative method of canning, precaution must be taken to presterilize the system by known techniques. Presterilization of the system may be efiected by passing water through the heat exchanger to. processing temperatures and the hot water through the flow divere sion valve 20 to the discharging chamber 21 (vacuum omitted) where it is removed by pump 22 to the aseptic. canning unit .which is independently sterilized by conven: tional means. When the product is aseptically canned; the homogenizing and retorting operations areomitted.

In the following examples illustrating .the methods of practicing this invention it will be -understood that the. flow rates and times may be varied for heating theprodnet to effect substantial coagulation of the eggyolk proteins without developing abnormally high consistencies.-

Example I had a consistency of 5,000 centipoises.

Example II A mixture ofegg 'yollrs, salt and water, containing 25.75% total solids, was treated under the same conditions as inExample I, except (a) the flow rates through the system were varied from pounds to 160 pounds per minute, and (b) each lot was split so that one-half was homogenized and the other not homogenized prior to canning. The results were: 1

Flow Total Consistency in Ceutipoises Rate, Heating Solids In Lot No. Pounds Time In Finished Per Seconds Product Not Homog- Homogenlzed Minute I enized e as fighting the rp sst n q es res orm nt empera e l idieatst st 29;. i nific nt ifiersnss xi ts; n m s lids co ten r sas s nw t efinish dpr ra e ar nsfiswats a us d Fur h r. the he ts r 9! hta iasr he. es r d. mpe atu a e varied from at u ims sl sawndstp i esame th:- vt nbstasttsllrmounta ns; Hampsenization of the product prior to canning imparted a Slightly smoother texture to the resultant product. If desired, the mixture may be homogenized, but it is not a necessary element of the invention.

Example III A mixture of 42.9% total solids, at a flow rate of pounds per minute, was heated to 350 F., flash cooled to 70 F., homogenized, cannedand retorted. The product contained 50.1% total solids, was smooth and creamy in texture, and had a consistency of 15,000 centipoises.

Example V A mixture containing 26.3% total solids was pumped through the indirect heat exchanger at a flow rate of 40 pounds per minute, heated to 310 F. and immediately cooled by flash evaporation to a temperature of F. The cooled product was split into two lots. Lot A was aseptically canned and lot B was canned in the conventional manner and retorted. The product from lot A was very fluid with a consistency of 500 centipoises, while the consistency'of lot B had increased to 3,500 centipoises after retorting. Both products were homogeneous,

smooth in texture and shelf-stable, without any significant.

viscosity increase after extended storage at room temperature. This example illustrates that egg yolks which have,

been substantially coagulated prior to canning are sus ceptible to viscosity increases if subjected to subsequent heat treatment as in retorting for eifecting commercial It.

sterilization of the conventionally canned materials. is the effective control of this subsequent viscosity increase that is lacking in prior art methods, but which is had' with our process.

In the above examples, the consistency was measured by a Brookfield viscometer. Prior to taking the viscosity reading, each sample was mixed with a spatula having a, The viscosity reading Ar-inch bladefor 2-4 revolutions. of the viscometerwas obtained by using a No. 7' stirrer for 4. dial revolutions at 20 r-.p.m. prior to reading.

The v above examples illustrate that egg yolk-water mixtures, which have been heated in the indirect heat exchanger to exit temperatures varying from about 310 F.

to 350 F; with formulations containing between 5% to 50% egg yolk solids give acceptable products. Our preferred temperature range is 3l0-330 F. for consumer type products containing 20-35% egg yolk solids. In-

. stallations which retain the product within the heating inyention lies in the, combination of treatment ofegg yolks at elevated temperatures plus immediate flash evap: oration to cool thev heat treated product, for we have,

o nd hat it s. not-sa isfact ry. o h at e. product tov only such limitations should beimposedas are indicated.

a he pgenda ai n- Eon examp he indirect, heater 18 described might be replaced by a Volator, which is well known in the art, although withless desirable results.

We claim: i

In the processing of egg yolks to obtain a product of smooth consistency, the steps comprising: forming a mixture of egg yolk and water with egg yolk solids comprising approximately 5% to approximately 50% of said mixture; heating said mixture by indirect heat exchange to a temperature above 310 F. but below 350 F.; immediately rapidly cooling by flash evaporation the heated mixture to a temperature between about 70 F. and 130 8 F.; thereafter canning said mixture and retorting said canned rm'xture to ate'mperature suflicient to commercially sterilize said mixture. 7 Y

References Cited in the file of this patent UNITED 'STATES' PA TENTS V Hawk Dot. 9, 1956 OTHER REFERENCES Food'Engineering, August 1953, p. 143, article entitled Strained Egg Yolk Product. 

